Inside Blake Lively and Ryan Reynolds' 'Super Supportive' Marriage as They Mark 12th Anniversary (Exclusive)

Ryan Reynolds and Blake Lively continue to support each other 12 years into their marriage.

The couple mark their wedding anniversary on Sept. 9, after a summer that saw both actors and producers reach new levels of success with their hit films Deadpool & Wolverine and It Ends With Us.

As Reynolds, 47, and Lively, 37, mark a marriage milestone, a source tells PEOPLE, "Blake and Ryan are a great team when it comes to both their family and work."

"They're super supportive of each other," the source adds. "He's very proud of her. They have a great marriage and love to celebrate everything they created together."

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer​​, from celebrity news to compelling human interest stories. 

Reynolds and Lively share daughters James, 9, Inez, 7, and Betty, 4, as well as baby son Olin. The couple met on the set of their 2011 movie Green Lantern and later married on Sept. 9, 2012.

Lively previously told PEOPLE about the romantic gestures Reynolds would make when they first started dating. "He would send me a bouquet of flowers every week," she recalled. "But he would always send a card and it would just be a sentence of something that had happened that week. Something funny or emotional that one of us said."

"It was just a little quote of the week," she added at the time. "It was such a beautiful, romantic thing. Now we have 4,000 children!"

As parents to four kids, Reynolds said during a July appearance on Live with Kelly and Mark that he and Lively spend their date nights mostly discussing their children.

"We went on a date the other night and our oldest was going to kill us," Reynolds recalled during that appearance. "Just for going on a date; just for tending to the relationship. And we did, and what’s crazy is, the whole time we’re there, we just talked about [our kids], when you think you’re going to be talking about [something else]."

Lively and Reynolds were most recently seen out and about in New York City on Sept. 5; to celebrate Lively's 37th birthday in August, they spent a weekend in Rhode Island with friends.